Hot air dryer



Jan. 29, 1957 A. L. PARK 2,779,105

HOT AIR DRYER Filed Aug. 10. 1953 P 35 INVENTOR.

ATTORNEV Unit nor Am DRYER Application August 10, 1953, Serial No.373,242

(Ilairns. (Cl. 34-455) This invention relates to hot air dryers and moreparticularly to a novel hot air dryer especially suitable for use indrying an extended sheet of sized textile yarns as in a slasher.

In the drying of textile yarns such as cotton or Wool, particularly in aso-called wet splitting slasher, it is desirable to keep the severalthousand individual yarns of the yarn sheet separated from one anotheras much as possible, and particularly so in the initial stages of dryingthe sized yarns to a non-tacky condition. Various complicated means havebeen proposed for achieving this result, but the most practical approachto the problem has been by the use of a hot air type of dryer whichwould allow some vertical separation of the yarn sheet as well as thehorizontal separation common to both hot air and cylinder dryers. Suchuse of vertical separation made possible by the use of a hot air dryerhas greatly aided in keeping separate the individual yarns while thesize coating was dried to give a superior yarn less subject to breakingand shedding in the loom.

As slasher speeds and capacities increased, however, the use of hot airdryers began to present a problem due to the tendency of such dryers tocondense the yarn sheet laterally, especially at the outer edges,causing the yarns to come in contact with one another. This effectresulted not only in substantially slower drying of the yarns but, moreimportant, caused the yarns to stick together with resultant problems inthe loom. Fine yarns under low tensions, especially with the higherdryer air velocities necessary to secure high production rates, wereparticularly susceptible to twisting around each other, with the yarnsheet sometimes assuming a rope-like appearance at the edge portions.

Thus, heretofore, the dryer air velocities have been limited by theamount of lateral condensation of the yarn sheet which could betolerated. This has required that the size of the hot air dryer beincreased in order to achieve desirable high dryer speeds andcapacities, and the resultant high speed, high capacity dryers havebecome too large for use in many locations.

Accordingly, it is an object of the present invention to provide a novelhigh capacity hot air dryer of reduced size as compared to heretoforeknown dryers having similar capacities.

A particular feature of my novel dryer is its ability to dry separatedyarn sheets without any lateral condensation whatsoever or with a degreeof lateral expansion if.

so desired.

It is a further feature of my novel dryer that it may readily beadjusted according to the nature of the yarn sheet to be dried and itsspeed of travel.

For the purpose of explaining a preferred embodiment of my invention,reference is made to the following detailed description, together withthe accompanying drawings, in which:

; Fig. 1 is a somewhat diagrammatic plan view of the novel dryer of myinvention;

rates Patent 2,779,105 Patented Jan. 29, 1957 head end (not shown) beingprovided for moving the extended yarn sheet S through the dryer.

A pair of plenum chambers are mounted horizontally in said enclosurewith their working faces opposed, and provide the air distributing meansfor the dryer, the upper plenum chamber 10 of said pair being mountedadjacent the top of said enclosure and the lower plenum chamber 12 ofsaid pair being mounted below in opposed spaced relation from upperplenum chamber lit, the space between the plenum chambers thus forming ahorizontal passage for the extended sheet of yarns S. Both of saidplenum chambers are spaced from the sides of said enclosure andpreferably from the output end thereof.

The plenum chambers 10 and 12 are identical in construction and includea generally rectangular enclosure having horizontal working surfacesforming upper and lower surfaces of the passage through which the sheetof yarns passes. The working surfaces of said chambers have a pluralityof transversely extending horizontally spaced members 14 forming aplurality of louvres 16 extending transversely of the dryer, the louvresforming openings through which the drying air is distributed over theextent of the yarn sheet S, such an air distributing means providing asmooth non-turbulent air flow which is most effective in its dryingaction of the yarns passing between and spaced from said surfaces. Inorder to provide generally uniform air flow within the plenum chamberitself so that each louvre 16 is provided with air at substantially thesame pressure, the top and bottom of said chambers are constructed closetogether at the end opposite the input end of such chamber.

The pair of plenum chambers are provided with a heater and blower 18having output ducts 20 and 22 to plenum chambers 10 and 12,respectively, and a return duct 24 from the end of the yarn passage backto said heater and blower to provide heated air to said plenum chambersand to exhaust the air from the yarn input end of the yarn passage, thusproviding a flow of air countercurrent to and along the direction ofmovement of said yarn sheet. Further means are provided for continuouslyexhausting moisture laden air from said dryer and for intake of freshair. Accordingly, an exhaust duct 26 is provided connected to the yarnpassage return duct 24, said duct being provided with a damper 28 whichmay be operated by any suitable means, not shown. When such exhaustdamper is open to allow air to be exhausted from the dryer, fresh air isdrawn into said dryer through opening 6 therein. The blowers of saidheater and blower mechanism are well understood by those skilled in theart and may be driven by any suitable means herein shown as an electricmotor 30.

According to my invention, to prevent lateral condensation of the yarnsheet as it passes through the dryer, I have provided air deflectingmeans at the sides of the yarn passage spaced outwardly from the sheetof yarns, such air deflecting means acting to displace laterallyoutwardly the yarns near the outer edges of the yarn sheet, thusenabling me to use high dryer air velocities and so reduce the physicalsize vof a dryer'of a given capacity.

A simple and effective air deflecting means may be provided by aplurality of bafiie plates 32 mounted within the enclosure 2 at thesides of the yarn passage outside of the side surfaces of plenumchambers 10 and 12, the surfaces of such baffle plates being generallyvertical with their inner edges 34 displaced forwardly from their outeredges 36 toward the flow of air created by heater and blower 1% throughthe yarn passage. For example, if the air flow is countercurrent to thedirection of movement of the sheet of yarn, as is preferred, the inneredges 34 will be displaced toward the yarn output opening 6 in enclosure2.

Since the optimum angle of displacement of the baffle plates 32 and theoptimum spacing of their inner edges 34 from the outer edges of the yarnsheet S will be determined by the nature of the yarn sheet to be driedand the operating characteristics of the dryer, 1 have provided a bafiieplate adjusting means (Fig. 3) in which said baffie plates are mounted,said means comprising a pair of relatively movable angle irons, with thebase webs 45 in stacked position, the inner upstanding web 37 of theinner angle iron and the outer upstanding web 38 of the outer angle ironhaving slots 4% and 42, respectively, adapted to receive a baffle plate32. A slot 44 is provided in each of the base webs 45 of said angleirons to permit relative adjustment of the slots 4%) and 42 to a desireddisplaced relation, at which said angle irons may be locked by a machinescrew 46 which also serves to mount said angle irons on said enclosure2.

in operation, with a sheet of yarns S being moved through the passagebetween the opposing working faces of plenum chambers 10 and 12 as by aconventional slasher head end, the baffle plates 32 are adjusted at saya displacement angle of 45 to the longitudinal axis of the yarn sheetwith their inner edges an inch or two from the outer edge of the yarnsheet near the input end of the dryer. The edge of the yarn sheet alongthe entire extent of the baffle plates will then expand from itsnormally condensed condition and the lateral spacing of the individualyarns from one another may be maintained or even increased somewhatduring the passage of the yarn sheet through my novel hot air dryer.

Although I do not wish to be bound thereby, I believe that the action ofthe bafiie plates to expand the yarn is due to the Bernoulli efiect,that is, the baffle plates act much as does an airfoil and create aregion of reduced pressure along their inner surface behind their inneredge 34. Thus, the angle of displacement from the direction of air flowthrough the yarn passage between the plenum chambers can be consideredas an angle of attack with the baffle plate inner edge 34 as the leadingedge. Under such conditions, there will be created a force generallyperpendicular to the baffie plate, which force will act to move theyarns near the outer edge of the yarn sheet toward the baffle plate. Theangle does not in practice appear to be critical, as I have effectivelyemployed angles from 20 up to 80; Since the effective force created bythe baflle plate falls ofi rapidly with distance, however, the leadinginner edge 34 of the plate should be quite close to the outer edge ofthe yarn sheet, say 1 or 2 inches, but in no event more than about 5inches with dryer air velocities of about 800 F. P. M. The outwarddisplacement of the yarn edge may be increased by decreasing thedistance between the baifle plate inner edge 34 and said yarn, but ifsuch distance becomes much less than inch there is danger of the yarns,

being damaged by contact with the bafile plates.

It will be seen that I have provided a novel high capacity hot air'dryerwhich for the first time makes possible the drying of yarn sheetswithout any lateral condensation thereof, and one which may readily beadjusted to accommodate almost any conditions. Although I have shown anddescribed herein a preferred embodispirit of my invention and the scopeof the appended claims.

I claim:

1. A hot air dryer for continuously drying an extended sheet of yarnspassing therethrough comprising air distributing means in opposed spacedrelation forming a passage for an extended sheet of yarns movingthere-between, blower means for providing a how of air along said sheetof yarns, and a plurality of spaced air deflecting bafile plates at theside of said passage and spaced from said yarn sheet to deflectoutwardly said fiow of air near the sides of said passage and displacelaterally outwardly the outer edge portions of said yarn sheet, thesurface of said baffie plates being generally perpendicular to thesurface of said yarn sheet and with their inner edges displaced fromtheir outer edges in a direction toward said flow of air.

2. A dryer as claimed in claim 1 in which said air distributing meansincludes a pair of plenum chambers each having a working face comprisinga plurality of transversely extending spaced members providing aplurality of louvers.

3. A dryer as claimed in claim 1 further having baffle plate adjustingmeans for adjusting the degree of displacement of said bathe plate edgesand the spacing of said inner edges from said yarn sheet to vary theoutward lateral displacement of said yarn sheet.

4. A hot air dryer for continuously drying an extended sheet of yarnspassing therethrough comprising a pair of plenum chambers with theirworking faces in opposed spaced parallel relation forming a passage foran extended sheet of yarns moving therebetween, heater and blower meansfor supplying heated air to said plenum chambers and exhausting air fromone end of said passage to provide a flow of air along said passage, anda plurality of spaced air deflecting baffie plates at the sides of saidpassage and spaced from said yarn sheet to deflect outwardly said flowof air near the sides of said passage and displace laterally outwardlythe outer edge portions of said yarn sheet, the surface of said bafiieplates being generally perpendicular to the working faces of said plenumchambers, and with their inner edges displaced from their outer edges ina direction toward said flow of air.

5. A hot air dryer for continuously drying an extended sheet of yarnspassing therethrough comprising an insulated enclosure, a pair of plenumchambers mounted within said enclosure with their working faceshorizontal and in opposed spaced relation forming a horizontal passagefor an extended sheet of yarns moving therebetween, heater and blowermeans for supplying heated air to said plenum chambers and exhaustingair from the yarn inputend of said passage to provide a how of heatedair along said sheet of yarns generally countercurrent thereto, aplurality of spaced air deflecting bafiie plates mounted within saidenclosure at the sides of said passage and spaced from said yarn sheetto deflect outwardly said countercurrent flow of air near the sides ofsaid passage and displace laterally outwardly the outer edge portions ofsaid yarn sheet, the surface of said baffle plates being generallyvertical, and with their inner edges displaced from their outer edgestoward said countercurrent flow of air.

References Cited in the tile of this patent UNITED STATES PATENTS1,737,015 Merrill Nov. 26, 1929 2,083,141 Buck June 8, 1937 2,303,019Hanson Dec. 22, 1942 2,574,083 Andrews Nov. 6, 1951 2,601,080 AndrewsJune 17. 1952

